1. Field of the Invention
The present invention relates to a linear guide bearing apparatus which is used as a linear guide in a machine tool and industrial machines.
2. Description of the Related Art
As a linear guide bearing apparatus which is used as a linear guide in a machine tool and industrial machines, there is conventionally known a guide bearing apparatus which includes a guide rail, a slider serving as a movable element, and a plurality of balls serving as rolling elements.
In the conventional guide bearing apparatus, the guide rail extending in the axial direction of the apparatus includes two first raceway grooves respectively formed in the two side walls thereof. The slider includes not only two second raceway grooves disposed opposed to the first raceway grooves of the guide rail but also ball return grooves respectively connected continuously with the second raceway grooves through their associated curved grooves respectively formed in the two end portions of each of the second raceway grooves. The slider includes a slider main body and a pair of end caps respectively to be connected to the two end portions of the slider main body; and, the second raceway grooves and ball return grooves are respectively formed in the slider main body, while the curved grooves are respectively formed in the end caps. This slider can be disposed by fitting the guide rail with the slider from the upward direction thereof in such a manner that the slider can be moved freely. The plurality of balls are used to move the slider along the guide rail, while the balls are disposed in a circulation passage which is composed of the first raceway grooves, second raceway grooves, curved grooves and ball return grooves.
In the linear guide bearing apparatus, in order to prevent dust from entering the circulation passage, there are disposed long-and-narrow-plate-shaped under-seals for sealing the two side walls of the guide rail and the two inner walls of the movable element. These under-seals are mounted on the lower wall of the slider along the axial direction of the guide bearing apparatus.
As a mounting structure for mounting the under-seals, there is conventionally known a mounting structure in which under-seal support grooves are formed in the end caps and the two end portions of the under-seals are respectively inserted into the under-seal support grooves.
However, in the above conventional mounting structure, in case where the two end portions of the under-seals are respectively inserted into the under-seal support grooves to thereby support the under-seals, the long-and-narrow-plate-shaped under-seals receive downward-going forces due to their own weights and the longitudinal-direction middle portions thereof are thereby flexed, which raises a fear that a poor sealing condition can occur.